WASHINGTON In a setback for environmentalists, Supreme Court justices signaled they will throw out a huge global warming lawsuit brought by California and five other states that seeks limits on carbon pollution from coalfired power plants in the South and Midwest.

Encouraged by the Obama administrations top courtroom lawyer, the justices said the problem of regulating greenhouses gas should be left to the Environmental Protection Agency. It is too complex and unwieldy to be handled by a single federal judge acting on a public nuisance lawsuit, some of them said.

A defeat for the lawsuit would put more pressure on the administration and the EPA to enforce limits on carbon pollution in the face of strong opposition from congressional Republicans, environmental advocates said.

The stakes will be very high. The question is whether they can deliver, said David Doniger, a climatechange expert for the Natural Resources Defense Council.

The issue debated before the high court Tuesday was not whether greenhouse gases are causing global climate change, but who should regulate theses gases. The decision involves politics, economics and science, the lawyers said.

Its a question of tradeoffs, said Peter Keisler, a lawyer representing the power producers. There is no legal principle here to guide the decision if it were made by a judge. Solicitor General Neal Katyal in urging the justices to throw out the lawsuit against the power plants as too sprawling.

In the 222 years that this court has been sitting, it has never heard a case with so many potential perpetrators and so many potential victims, Katyal began. Everyone on the planet is an emitter of carbon dioxide, he said, and everyone is a potential victim of global warming. Judges and courts are not suited to handling global problems through a lawsuit, he said.

In their comments, it became clear that the justices liberals and conservatives alike were dubious about allowing a single judge to decide on the regulation of greenhouse gases.

This sounds to me a lot like what the EPA does, Justice Ruth Bader Ginsburg told a New York state lawyer who was defending the lawsuit. A judge cannot be a super EPA who sets and enforces detailed regulations, she said.

Four years ago, the justices cleared the way for the EPA to regulate greenhouse gases under the Clean Air Act. Since then, the government has adopted stricter standards for new motor vehicles, which take effect next year. But regulation of power pla handbag designers nts has stalled. The agency says it will propose new rules in July.

All the while, the states have pressed a handbag designers head with their nuisance suit against the five large power producers. handbag designers

Lawyers for California, Connecticut, New York, Rhode Island, Vermont, Iowa and New York City sued the power plants that were responsible for 10 percent of the nations carbon emissions. They said these gases are causing the planet to heat up, posing a threat to the coastal communities in the East and West, and to crops in the heartland. It asked for a judge to impose limits on these emissions.

Four more states Illinois, Maryland, Massachusetts and North Carolina endorsed the suit when it reached the high court. But 23 other states, led by Indiana, said the suit poses a political question that should not be resolved by a judge. The first judge who heard the suit dismissed it. Court of Appeals in New York revived it. Though the case had not gone to trial, the Supreme Court voted last year to hear the power industrys contention that it should be thrown out. The case is American Electric Power Co. v. Connecticut. handbag designers